Originally, it was to be a stop-motion comedy about a Stone Age genius. Fast-forward eight years and it's now a 3-D adventure comedy about the 'first modern family,' big brows, beasts and all.

In May 2005, DreamWorks Animation SKG and Aardman Animations announced that, following their collaborations on "Chicken Run," "Wallace & Gromit: The Curse of the Were-Rabbit" and "Flushed Away," their next joint venture would be "Crood Awakening," a stop-motion comedy about a caveman living in a small village with a prehistoric genius.

John Cleese of Monty Python fame and Kirk DeMicco ("Racing Stripes") were hired to write the script.

And now nearly eight years later, a vastly different version of the tale is opening Friday. Instead of a buddy film, "The Croods" is a 3-D adventure comedy about the "first modern family" — not Stone Age people with modern conveniences, a la "The Flintstones," but a group of characters with bad teeth and massive brows, arms and foreheads who are trying to keep their family unit intact in an often-hostile environment.

The patriarch, Grug (Nicolas Cage), who lives by the motto "Fear is good; change is bad," has managed to keep his family alive from the beasts that stalk them as prey every time they leave the safety of their dark cave. But he's at wit's end with his feisty teenage daughter, Eep (Emma Stone), who is sick of being confined to the cave and wants to explore her surroundings.

Rounding out the Croods are Grug's loving wife, Ugga (Catherine Keener); a dumber-than-a-stump son, Thunk (Clark Duke); toddler daughter Sandy, who has the tenacity of a terrier; and a wisecracking mother-in-law, Gran (Cloris Leachman).

When their cave and canyon surroundings are destroyed, the Croods are forced to go on a journey with the help of a young man named Guy (Ryan Reynolds), who has discovered the use of fire.

So how did "Crood Awakening" evolve into "The Croods"?

"There was a very simple kernel of an idea about an advanced genius in prehistoric times who is saddled with a primitive Luddite," DeMicco recalled.

He and Cleese worked on early drafts — Cleese has a story credit on "The Croods" — and shortly after Aardman and DreamWorks parted ways in early 2007, Chris Sanders left Disney, where he had co-directed the 2002 animated hit "Lilo & Stitch," and began working with DeMicco on the film at DreamWorks.

The concept, Sanders said, "was really cute." But despite their efforts, he added, "The story wouldn't quite lift off the ground." He moved on to direct DreamWorks' Oscar-nominated 2010 blockbuster "How to Train Your Dragon."

It was while he was in production on "Dragon" that DeMicco evolved the "Crood" story into a tale about a family. Sanders loved the idea, and when "Dragon" took flight, the two began working on the project in earnest. They share writing and directing credit on the finished product.

Once they had their story, the challenges weren't over. In animation, DeMicco noted, the plot usually "follows a single character or maybe two. There are a lot of buddy movies. But an ensemble comedy? It's super-hard."

The Croods "are on the screen the entire time," he said, "and because it's an ensemble comedy, you have to track every single one from scene to scene. You can never take it easy or cut away to the villain."

And there was the matter of character design. The Croods look less like "The Flintstones" and more like the denizens of "Quest for Fire."

"We had a lifetime opportunity to design cavemen," Sanders said. "And CGI cavemen would be much more believable than any cartoon cavemen. We did take our cue from books and from real cavemen references."

Eep, he said, was probably the toughest design for them to nail down: "We wanted her to be pretty, but we didn't want her to be princess pretty."

Sanders and DeMicco haven't forgotten the "aww" factor in "The Croods," populating the comedy with a vast array of hybrid animals including a macawnivore, which has the body of a huge tiger, a big head and the coloring of a macaw parrot; a bear owl that sleeps during the day and prowls at night; piranhakeets, a cross between a parakeet and a piranha; and punch monkeys, which pack a wallop when threatened.

The filmmakers wanted the Croods to encounter unusual animals, "because we wanted the audience to be on the same level as the characters," Sanders said.

"The whole movie is about the Croods seeing things for the first time," DeMicco said. "They are shocked, amazed and afraid of these new things, and we wanted the audience to have the same experience. We thought it would give them the chance to not only see the world through the cavemen's eyes, but also kind of sympathize and reconcile Grug's paranoia and fear. Everything we tried to do was to put the audiences in their shoes, so to speak."